The percentage of perfume retained in the headspace over a bar surface (specifically, the perfume headspace concentration, after storage, divided by perfume headspace concentration at initial time zero) measured after storage at 50° C. for one month can be defined as “perfume headspace retention”. Enhanced retention in a bar is important because it is correlated with enhanced fragrance activity that perceived by consumers, presumably because less perfume (especially top note perfume elements) is lost.
There are a number of references relating to fragrance loss.
U.S. Pat. No. 6,336,553 to Gordon discloses packages that prevent fragrance or moisture loss during storage.
JP 10060482 to Givaudan Roure Int. discloses a perfume carrier comprising a solid water-insoluble inorganic carrier, a perfume composition, a perfume thickener soluble in water, and a perfume for limiting the loss of a perfume during storage of a bar.
Various references relate to reducing overall soap level (total fatty matter, TFM) using structuring technology. These references include as follows:
WO 01/42418 to Chokappa et al. discloses a detergent bar containing 0.5 to 30% amorphous alumina, one alkali metal salt of carboxylic/sulfonic acid, 5-70% detergent active and 10-55% water.
U.S. Pat. No. 6,207,636 to Benjamin et al. discloses detergent bars having 25-70% total fatty matter, 9-16% by weight colloidal aluminum hydroxide and 12-52% water. The invention also comprises a process for preparing a detergent bar.
WO 2006/094586 to Gangopadhayay et al. discloses a low TFM detergent bar including soap (15% to 30% TFM); 25% to 70% inorganic particulates including talc and calcium carbonate; 0.5% to 10% of alumino-silicate; and 3% to 20% water.
U.S. Pat. No. 6,310,016 to Behal et al. discloses a detergent bar including soap (15-70% total fatty matter); 0.5-40% colloidal aluminum hydroxide-phosphate complex, and 10-50% water. A process for making such bars is also disclosed.
U.S. Pat. No. 6,440,908 to Racherla discloses high moisture containing bar compositions that includes a borate compound. The borate compound structures water in the bar thereby enabling the retention of high amounts of moisture without compromising bar properties.
WO 2005/080541 to Gangopadhayay et al. discloses a non-granular solid cleaning composition comprising 50% to 70% of a salt of fatty acid; 1% to 15% of a mono- or disaccharide; and 0.02% to 2% of a stabilizing agent. Preferred saccharides are glucose, sucrose, mannose, and fructose and the stabilizing agent is preferably chosen from the class of fungicides including formaldehyde, benzoic acid and salts thereof and methyl or ethyl paraben.
WO 03/010272 to Anderson et al. discloses soap or detergent bar having relatively low levels of total fatty matter (40% to 78%), allowing relatively high levels of water (7% to 30%) and/or other liquid additives to be present by incorporating aluminum hydroxide and tetra sodium pyrophosphate decahydrate into the bar. Methods of producing such bars are also disclosed.
WO 96/35772 to Wise et al. discloses laundry bar compositions including from about 20% to about 70% surfactant; from about 12% to about 24% water; from about 6.25% to about 20% calculated excess alkali metal carbonate; from about 2% to about 20% water-soluble inorganic strong-electrolyte salt; and various optional ingredients including whole-cut starch.
WO 95/26710 to Kacher et al. discloses personal washing bar compositions that include about 5 parts to about 40 parts of a lipid skin moisturizing agent; about 10 parts to about 50 parts of a rigid crystalline skeleton network structure consisting essentially of selected fatty acid soap or a mixture of said soap and selected fatty acid; about 1 part to about 50 parts of a lathering synthetic surfactant, and; about 10 parts to about 50 parts water.
WO 98/18896 to Rahamann et al. discloses high moisture laundry bar composition including from about 45% to about 95% structured soap composition, wherein said structured soap composition comprises a premixture of from about 45% to about 75% soap; from about 5% to about 50% starch; about 25% to about 45% moisture; and wherein the ratio of starch to moisture in said structured soap composition is from about 1:5 to about 1.25:1; and from about 1% to about 15% synthetic anionic surfactant; wherein the total moisture in the finished bar composition is from about 20% to about 40%.
U.S. Patent Nos. 2007/0021314 and 2007/0155639 to Salvador et al. disclose cleansing bar compositions having high water content that include (a) at least about 15% by weight of the composition of water; (b) from about 40% to about 84% by weight of the composition of soap; and (c) from about 1% to about 15% by weight of the composition of inorganic salt. The bar compositions further comprise a component selected from the group consisting of carbohydrate structurant, free fatty acid, synthetic surfactants, and mixtures thereof. The bar compositions preferably have a Water Activity (“Aw”) of less than about 0.95, preferably less than about 0.90, and more preferably less than about 0.85. The bar compositions are preferably manufactured by a milling process.
In general, when the predominant surfactant in the personal washing bar is fatty acid soap, a reduction in surfactant is commonly expressed as reduction in “Total Fatty Matter” or TFM. The term TFM is used to denote the percentage by wt. of fatty acid and triglyceride residues present in soaps without taking into account the accompanying cations. The measurement of TFM is well known in the art. A “low” TFM bar is typically one which will have <70%, preferably <65%, more preferably <60% and even more preferably <55% TFM.
There are references which do disclose generally extruded bars with low TFM and comprising structuring systems like those of the invention. GB Application No. 806340.6 to Leopoldino (Unilever), filed Apr. 8, 2008, for example, discloses low TFM extrudable soap bar compositions which include starch, polyols and optionally water insoluble particles. Perfume is an optional ingredient which is recited in a long list of many, many possible optionals and there is no disclosure or suggestion that there is any benefit (i.e., enhanced perfume retention) to using perfume in such bar compositions relative to any other bar compositions.
As indicated, applicants have filed copending Great Britain Application No. 0806340.6 to Leopoldino et al., entitled “Extruded Soap Bars Comprising a Composite Starch-polyol Structuring System”. Applicants have also filed Great Britain Application No. 0901953.0 to Canto et al., entitled “Low TFM Extruded Soap Bars Comprising Starch Polyol Structuring System”.
Neither reference discloses or recognizes the unexpected enhanced perfume storage retention which occurs when using low TFM starch-polyol bars relative to other bar compositions.
Quite unpredictably, however, applicants have found that, when perfume is used in such specific, low TFM, starch-polyol structured systems (comprising, for example, 5 to 30% preferably 6 to 25% by wt. polyol), there is found enhanced perfume retention during storage when compared to, for example, effect of the same perfume used in soap bars having >60% by wt. fatty acid soap.
While not wishing to be bound by theory, applicants believe that polyols (required for reducing TFM using starch-polyol structuring system) are good solvents for the perfume oils and, because the perfume is dissolved, this typically results in lower perfume headspace over the bar. This “suppression” also means, however, that less perfume is lost into the vapor phase during storage. It is believed that this “suppression” effect of polyols on perfume headspace disappears when the bar is diluted. Thus, quite unpredictably, the use of high polyol level in the low TFM starch-polyol system actually ends up retaining more fragrance during storage than conventional bars without starch-polyol system. In higher TFM bars (>60% fatty acid soap), the same enhancement is not observed.